0.1 mu m contact metallization with SiH/sub 2/F/sub 2/-reduced CVD W

Abstract

The fabrication of fine contact metallization down to 0.08 mu m in diameter for future 0.1- mu m-level ULSIs is discussed, and the electrical characteristics are evaluated. A two-layered etch mask, PMMA/poly-Si, was used for electron-beam delineation. Low-temperature dry etching permits the accurate patterning of the poly-Si layer in accordance with the PMMA mask, by increasing the PMMA etch-rate selectivity from 0.63 in ordinary dry etching to 15. Contact holes as small as 0.08 mu m in diameter are opened following application of the poly-Si as a mask. The combination of SiH/sub 2/F/sub 2/-reduced blanket CVD W (0.2 mu m thick)/sputtered W (30 nm thick) is used for metallization. Typical resistances are 1.5 k Omega on a 0.13- mu m-diameter contact to p/sup +/-Si and 107 Omega on a 0.18- mu m-diameter contact to n/sup +/-Si. Contact resistivities of these 0.1- mu m-level contacts are of the same levels as those of holes with diameters larger than 0.25 mu m.<>